FR2890965A1 - AMMONIACAL HYDROLYSIS OF METHIONINE HYDANTOIN WITHOUT CATALYST - Google Patents

Abstract

The present invention relates to a process for the preparation of methionine, continuously and without isolation of intermediate products, from hydantoin of methionine, by ammoniacal hydrolysis, without catalyst, of an aqueous starting solution which essentially comprises said hydantoin and at least one associated methioninogenic derivative product, for example selected from the group consisting of hydantoic acid, ureidobutyramide and 2-amino-4- (methylthio) butanamide. The hydrolysis takes place at a temperature of between 100 and 250 ° C., and starting from a molar proportion of NH 3 / hydantoin of between 5 and 50.

Description

The field of the present invention is that of the preparation of the acid

  2-amino-4- (methylthio) butanoic acid (hereinafter referred to as methionine) from 5- [2- (methylthio) ethyl)] - 2,4-imidazolidinedione (hereinafter referred to as methionine hydantoin) by hydrolysis ammonia.

  The formulas of these compounds are as follows: Hydantoin Methionine Methionine

OH NH2

  The process for the preparation of methionine has been going on for many years by the saponification of methionine hydantoin, that is to say its hydrolysis with NaOH, which has the drawback of generating a significant amount of sodium sulphate Na.sub.2SO.sub.4.

  An object of the present invention is to obtain methionine from methionine hydantoin without salt co-production.

  Research conducted for many years to obtain methionine without co-production of salt all required multiple steps of synthesis, separation, and / or a catalyst. In particular, patent application US 2004/0039228 describes a process for preparing the amino acids by hydrolysis of hydantoins in the presence of water, ammonia and at least one catalyst of the metal oxide type.

  It is an object of the present invention to provide a process for preparing methionine from hydantoin without isolating intermediates and without using a catalyst, for example a metal oxide catalyst.

  Patent FR 1 588 402 describes a process for the preparation of α-amino acids by hydrolysis of hydantoins, consisting in causing ammonia to act on a hydantoin, without catalyst. The process described involves the use of a hydantoin in purified form, which has a disadvantage in terms of industrial implementation, given the many associated derivatives, methioninogenic, accompanying hydantoin.

  Another object of the present invention is to provide an industrial process for the preparation of methionine.

  Another object of the present invention is to provide an industrial process from an aqueous industrial solution of methionine with the above-mentioned associated derivatives.

  Methionine hydantoin is generally obtained by hydrolysis of 2-hydroxy-4- (methylthio) butyronitrile (hereinafter referred to as HMTBN) in contact with ammonia water. This hydrolysis generates associated derivatives, in particular hydantoïque acid, ureidobutyramide and 2-amino-4 (methylthio) butanamide.

  The present invention provides a continuous process for the preparation of methionine from the hydantoin of methionine, wherein ammoniacal hydrolysis, without catalyst, is carried out of an aqueous starting solution comprising essentially said hydantoin and at least one associated derivative product, methionine, for example selected from the group consisting of hydantoic acid, ureidobutyramide and 2-amino-4- (methylthio) butananide.

  According to the present invention, said process used comprises the following four steps: According to step (a), the aqueous ammonia solution is hydrolyzed continuously in the aqueous homogeneous phase without isolating any products. intermediate, at a temperature between 100 and 250 C, and starting from a molar ratio NH3 / hydantoin of between 5 and 50, for example of the order of 20, to obtain an output mixture comprising principally the methionine, dissolved carbon dioxide and ammonia, and the unreacted starting materials.

  According to step (b), the outlet mixture is expanded, then the expanded outlet mixture is separated into a liquid stream enriched with methionine, and a gaseous stream enriched with ammonia and carbon dioxide.

  According to step (c), the liquid stream enriched in methionine is separated into solid methionine, evacuated, and mother liquors depleted in methionine and containing said unreacted starting materials, said mother liquors being recycled, after raising of their pressure, towards hydrolysis (a).

  According to step (d), the gaseous stream enriched with ammonia and carbon dioxide is separated into a gaseous fraction enriched with carbon dioxide, evacuated, and a recycled ammonia liquid fraction, after raising its pressure, towards hydrolysis. (at).

  Thanks to the method according to the present invention, and as shown in the experimental protocol established below, the methioninogenic derivatives of hydantoin are also hydrolysed, which in total generates a good yield of methionine from any aqueous industrial solution. hydantoin.

  FIG. 1 represents, generically, a methionine production plant, from an aqueous industrial hydantoin solution.

  Fig. 2 shows a methionine production plant according to one embodiment of the present invention.

  FIG. 3 is a graphical representation of the reaction kinetics of the hydrolysis of hydantoin of methionine in the presence of a catalyst at a temperature of 120 ° C.

  FIG. 4 represents, in graphical form, the reaction kinetics of the hydrolysis of the hydantoin of methionine in the presence of a catalyst, at a temperature of 160 ° C.

  FIG. 5 is a graphical representation of the reaction kinetics of the hydrolysis of the hydantoin of methionine in the presence of a catalyst and of NH 3 at a temperature of 120 ° C.

  FIG. 6 is a graphical representation of the reaction kinetics of hydantoin hydrolysis of methionine in the presence of NH 3 according to the invention.

  FIG. 7 represents the proportion of products at zero time and comparatively, that at 45 minutes, during the hydrolysis of the hydantoin of methionine in the presence of NH 3, according to the invention.

  The present invention is described in more detail in the following.

  The reactions used during the ammoniacal hydrolysis according to the invention can be schematically represented as shown below:

O NH2 NH2

2-amino-4- (methylthio) butanamide

NH

Hydantoin of methionine

O

OH NH2

  Methionine HNNH2 Hydantoïc acid

OH

O

  NH 2 HN NH 2 + NH 3 + CO2 Ureidobutyramide By "methioninogen" is meant any compound likely to lead to methionine by ammoniacal hydrolysis. According to the present invention, the aqueous hydantoin starting solution, the hydantoin being itself a methioniogenic compound, is furthermore capable of comprising methioninogenic derivatives, and in particular hydantoïque acid, urideobutyramide and 2- amino-4- (methylthio) butananide, shown above.

  By "catalyst" is meant any compound not consumed in the hydrolysis reaction and found completely when the reaction is complete. In general, there is no stoichiometric ratio between the catalyst and the reagents. In this case, the process that is the subject of the invention takes place in the absence of a catalyst, in a homogeneous or heterogeneous phase, which has considerable advantages, industrially speaking.

  By "continuous" is meant that the process is carried out with a continuous feed in aqueous starting solution. This further implies a continuous withdrawal of the products formed.

  By "without isolating intermediates" is meant that at no time during the ammoniacal hydrolysis step is an intermediate product isolated or separated. In addition to the fact that the hydrolysis step is fed continuously by the starting solution, it can be exchanged with the outside of the energy but not the material. This means that during the hydrolysis step, nothing other than the starting solution is added. This is very advantageous at the industrial level. In other words, the hydrolysis reaction is carried out in "one pot". According to the present invention, the ammoniacal hydrolysis is therefore carried out continuously, without intermediate separation or fractionation, and in a manner known per se, for example with a tubular reactor or a cascade of stirred reactors, arranged in series.

  The basic method according to the present invention is now described with reference to FIG.

  The process implements hydrolysis 1 continuously, in aqueous homogeneous phase. This hydrolysis proceeds without isolation of intermediates, as defined above. The hydrolysis 1 is fed with an aqueous solution 2, industrial, comprising mainly methionine hydantoin, but also the associated derivatives, methioninogenic hydantoïque acid, ureidobutyramide and 2-amino-4- (methylthio) butanamide (also called AMBTM). The feed of the reactor 1 in aqueous solution 2 is carried out via a feed pipe.

  Before introduction into the reactor 1, the aqueous solution 2 comprising the hydantoin is added an aqueous phase containing ammonia via the feed pipe 3, which is dissolved in the aqueous solution 2 comprising hydantoin, which is has previously raised the pressure by a pump 4.

  According to the present invention, while the temperature is set, the pressure is imposed to have a homogeneous liquid phase. The temperature is raised in reactor 1, at a temperature ranging between 100 and 250 C. For operation in the aqueous homogeneous phase, the pressure must be between 5 and 60 bar (preferably about 20 bar).

  The hydantoin / NH3 molar proportions are between 1/5 and 1/50, for example of the order of 1/20 at the inlet of reactor 1, and consequently with a very large molar excess of ammonia relative to hydantoin.

  An exit mixture comprising principally methionine, CO 2 and dissolved NH 3 is obtained at the outlet of reactor 1 by hydrolysis of the methionine hydantoin.

  This mixture is expanded, for example at atmospheric pressure, by an expansion valve 6, in line 5, before being introduced into a "stripping" column 10 (also called a steam distillation column).

  In column 10, the expanded mixture introduced is separated into a liquid stream 12 enriched in methionine and a gaseous stream 11 enriched in NH 3 and CO 2.

  At the column head 10, the gaseous stream enriched in NH 3 and CO 2 and which also comprises water, is separated into a carbon dioxide-enriched gas fraction 21, an ammoniacal gas fraction 22 and optionally a purge 23 It is possible, according to the present invention, for the purge 23 and the gaseous fraction 21 enriched with carbon dioxide to be united in one and the same conduit.

  The gaseous ammoniacal fraction 22 is condensed. The resulting aqueous phase, containing ammonia, is recycled to the hydrolysis reactor 1, via a feed pipe 3, and after lifting 7 of its pressure.

  It is also possible according to the present invention to provide a supply line 8 which feeds the pipe 3 with ammonia, before raising the pressure. Such conduct allows the adjustment of the ammonia titer if necessary.

  At the bottom of the "stripping" column 10, via the withdrawal line 12, a liquid stream enriched with methionine, i. e. an aqueous solution of methionine, "acidified", that is to say whose pH has been lowered.

  According to Figure 1, this stream is cooled in a heat exchanger 30, which allows to precipitate methionine. But any other means known to those skilled in the art, for example evaporation, is applicable in this case.

  The liquor thus obtained is then sent to a separator 40 which makes it possible to separate the methionine in solid form, unreacted products of hydantoin, remaining in the aqueous phase, called mother liquors.

  At 41, the methionine is recovered in solid form, while said by-products are returned to the reactor 1, via the supply line 42, after lifting of their pressure by the pump 43. This recycling loop is particularly advantageous as appears in the present invention.

  The basic method according to the present invention defined by reference to FIG. 1 is now specified with reference to FIG.

  According to one embodiment of the present invention, the gaseous stream enriched with ammonia, after condensation, is washed in a washing column 50, with an amine, for example monoethanolamine (MEA), diglycolamine, triethanolamine (TEA). or mixtures thereof, to obtain, on the one hand, a liquid part 51 enriched in carbon dioxide (ie in the form of amine carbonate), and on the other hand a gaseous part 52 enriched with ammonia, said liquid part enriched in carbon dioxide being then separated in a "stripping" column 55 of gaseous carbon dioxide 52 and of liquid amine 57 recycled to the washing column 50.

  In addition to the amines, it is possible, according to another embodiment of the present invention, to use other solvents such as N-methyl-2-pyrrolidone or the mixture of sulfolane and 1,1'-imino-bis. propanol.

  It is also possible to carry out absorption in potassium carbonate to form potassium bicarbonate. The latter by heating restores potassium carbonate and releases CO2.

  According to one embodiment of the present invention, the liquid stream 12 enriched in methionine is separated by staged crystallization 45 to obtain, on the one hand, solid methionine, filtered 46 and then dried 47, and on the other hand , mother liquors 42.

  According to one embodiment of the present invention, the hydrolysis 1 according to step (a) is carried out in a tubular reactor or in a plurality of stirred reactors (1a, 1b, 1c, 1d) arranged in series. as shown in Figure 2.

  The number of agitated reactors is indifferent. Preferably, it is greater than 3, but the maximum number is not limited.

  The following examples will make it possible to understand the advantage of the ammoniacal hydrolysis according to the present invention, and consequently the interest of a process according to the invention.

Examples

  In a stainless steel or Teflon reactor of 100 cm3, heated by a double jacket, and comprising: - a stirring and its pale counterpart, - a measurement of the internal temperature, - a measurement of pressure, - a sampling system under conditions of In operation, the hydantoin industrial solution which also comprises the methioninogenic associated derivatives (hydantoin, hydantoic acid, ureidobutyramide, AMTBM) and the catalyst (for the comparative examples), the NH 3 and the catalyst (for other comparative examples) or NH3 (for the examples according to the invention).

  Then it is heated to the temperature of the reaction.

  The progress of the reaction is followed by HPLC and electrochemical analysis of the samples.

  Conversion rate (for hydantoin and methioninogenic associates): (initial number of moles nb of final moles) / initial moles x 100 Yield (for methionine): moles of methanol obtained / moles Example 1 (AME 0070 and 0072): with catalyst For the following two tests, the following catalyst was used: TiO2 DT-51D TiO2 El MM TRILOBES C753-014 ENGELHARD This catalyst is ground in an aqueous medium and dried at room temperature. constant weight at 100 C. a) 120 C test (AME 0070) The titer of methioninogenic products (that is to say products likely to lead to methionine by ammoniacal hydrolysis) is of the order of 0, 5 moles per kg of reaction mass.

  The ratio catalyst / methioninogenic products is 191 g / mol.

  Time Hydantoin Acid Ureidobutyramide AMTBM Methionine (minutes) (moles / kg) Hydantoid (moles / kg) (moles / kg) (moles / kg) (moles / kg) 0 0, 323 0.059 0.104 0.010 0.010 1 0.318 0.064 0.102 0.011 0.012 0.318 0.064 0, 102 0.011 0.012 0.312 0.071 0.086 0.010 0.026 0.293 0.083 0.059 0.008 0.059 0.025 0.099 0.007 0.081 323 0.204 0.124 0.013 0.003 0.113 370 0.184 0.134 0.007 0.006 0.129 437 0.181 0.137 0.006 0.003 0.139 Figure 3 shows the kinetics of the reaction.

  b) Test at 160 C (MEA 0072) The titer of methioninogenic products is of the order of 0.5 mol / kg of reaction mass.

  The ratio catalyst / methioninogenic products is 183 g / mol.

  Time Hydantoin Acid Ureidobutyramide AMTBM Methionine (minutes) (moles / kg) Hydantoid (moles / kg) (moles / kg) (moles / kg) (moles / kg) 0 0, 339 0.062 0.109 0.010 0.010 0.306 0.067 0.050 0.009 0.074 0.181 0.061 0.003 0.003 0.200 0.066 0.028 0.001 0.001 0.301 146 0.014 0.008 LD 0.001 0, 368 214 0.003 0.001 LD 0.001 0.372 326 0.001 LD LD 0.001 0.428 391 LD LD LD 0.001 0.379 LD: limit of detection Figure 4 represents the kinetics of the reaction .

  Example 2 (Test AME 0093): with Catalyst and NH3 For the following test, the following catalyst was used: TiO2 DT-51D TiO2 El MM TRILOBES C753-014 - ENGELHARD This catalyst is ground in an aqueous medium and dried to weight constant at 100 C. Test at 120 C The title methioninogenic products is of the order of 0.537 mol / kg. The NH3 / methionine ratio is 13.25.

  183.69 g of catalyst / g of methioninogenic products.

  pH start 11.78 pH fine 11.3 Time Hydantoin Acid Ureidobutyramide AMTBM Methionine (minutes) (moles / kg) Hydantoid (moles / kg) (moles / kg) (moles / kg) (moles / kg) 0 0.352621641 0 , 095871405 0.059284769 0.004526989 0, 008590274 0.369590173 0.086250845 0.062379085 0.004115504 0.008248391 0, 343531167 0.121052905 0.063686275 0.003913102 0.03118294 0.286476868 0, 100036415 0.064522876 0,003036028 0,083758047 0,212145563 0,110856786 0, 052026144 0,003238429 0,126810622 0,137756859 0,096394944 0,038065359 0, 00148428 0,225858369 0,085925841 0,088851896 0,02530719 0,001619215 0 , 301636266 260 0,038973711 0,086823077 0,012601307 0,001146944 _0, 371378755 362 0,020261738 0,081204807 _ 6,74673E-05 _ 0,381638948 450 0, 013890483 0,081204807 _ _ 0,000202402 0.400348712 503 0.01274251 0, 07865578 0.00080961 0.37855418 550 0.014649673 0.088643812 0.005124183 6.74673E-05 0.424222103 LD: 500.0 x 10-6 mol / kg Figure 5 shows the kinetics of the reaction.

  Example 3 (Test AME 0094): according to the invention Test at 160 ° C. The titer of methioninogenic products is 0.549 mol / kg. The NH3 / hydantoin ratio is 20.3 starting pH = 11.36 End pH = 11.01 Based on the assay method used, this example only illustrates the fact that the addition of NH 3 increases the rate hydantoin hydrolysis and that there is no loss of the product.

  Time Hydantoin Acid Ureidobutyramide Methionine (minutes) (moles / kg) Hydantoid (moles / kg) (moles / kg) (moles / kg) 0 0.35330193 0.095045347 0, 058774034 0.008470697 0.372287912 0.099204078 0, 062588235 0.00798015 0, 270921823 0.050408365 0.058457516 0.189914163 0.087016416 0.05784737 0, 021281046 0.380029506 0.0394903 0.057483223 0.009882353 0.42972103 0, 017908392 0.039119804 0.005124183 0 , 428446888 0.009355987 0.023721584 0, 002718954 0.427373927 Figure 6 shows the kinetics of the reaction.

  The conversion rate of hydantoin is 88% at 45 minutes and 97% at 150 minutes.

  Example 4 (Test AME 0096) According to the Invention Test at 160 ° C. The titer of methioninogenic products is 0.516 mol / kg. The NH3 / hydantoin ratio is 21.47.

  Time Hydantoin Acid Ureidobutyramide AMTBM Methionine (minutes) (moles / kg) Hydantoid (moles / kg) (moles / kg) (moles / kg) (moles / kg) 0 0, 326 0.098 0.054 0.004 0.011 0.047 0.075 0.014 0.001 0.373 Figure 7 represents the proportion of products at time 0 and that at 45 minutes.

  Time Hydantoin Acid Ureidobutyramide AMTBM Methionine (minutes) Hydantoïc 0 0 0 0 0 2,28215768 85,5828221 23,4693878 40,8163265 75 77, 3858921 The table above shows the conversion rates of the methioninogenic products and the transformation yield of methionine.

  The conversion rate at 45 minutes of the hydantoin of methionine is 85.6%.

  The yield of the reaction at 45 minutes is 77.4%.

  Example 5 (Test AME 0097): according to the invention Test at 140 ° C. The title methioninogenic products is 0.538 mol / kg. The NH3 / hydantoin ratio is 20.7.

  Time Hydantoin Acid Ureidobutyramide AMTBM Methionine (minutes) (moles / kg) Hydantoid (moles / kg) (moles / kg) (moles / kg) (moles / kg) 0 0, 365167093 0.101365587 0.059852783 0.004654467 0, The table above indicates, at time 0 and in time 90 minutes, the title of the 10 compounds of the reaction.

  Time Hydantoin Acid Ureidobutyra AMTBM Methionine (minutes) Hydantoïque mide 0 0 0 0 0 1,78026142 92,1250451 39,5448112 79,5576857 98, 5504828 70,7424395 The table above shows the conversion rates of the methioninogenic products and the transformation yield of methionine.

  Compared with Example 4, according to the invention, it is found that the kinetics of appearance of methionine is equivalent for a double reaction time (45 minutes in Example 4 against 90 minutes in Example 5). This is because the test is carried out at 20 ° C. below that of Example 4. The influence of temperature is therefore important according to the present invention.

  It should be noted that the present results present a deficit on the balance sheet and are not 100%.

Claims (6)

  Process for the continuous preparation of methionine, from the methionine hydantoin, according to which an ammoniacal hydrolysis (1), without catalyst, of a starting aqueous solution (2) is carried out, characterized in that on the one hand, the aqueous starting solution essentially comprises said hydantoin and at least one associated methioninogenic derivative product, for example chosen from the group consisting of hydantoïque acid, ureidobutyramide and 2-amino-4- ( methylthio) butanamide, and secondly, the process used comprises the following steps: (a) ammoniacal hydrolysis (1) of the aqueous starting solution, in aqueous homogeneous phase, is carried out continuously and without isolating intermediate products, at a temperature between 100 and 250 C, and starting from a molar ratio NH3 / hydantoin of between 5 and 50, for example of the order of 20, to obtain an output mixture (5) comprising chiefly of methi onine, dissolved carbon dioxide and ammonia, and the unreacted starting materials; (b) the outlet mixture (5) is expanded (6), and the expanded outlet mixture (10) is separated into a methionine-enriched liquid stream (12) and an ammonia-enriched gas stream (11) and carbon dioxide; (c) separating (40) the liquid stream (12) enriched in methionine into solid methionine (41), evacuated, and mother liquors (42) depleted in methionine and containing said unreacted starting materials, said waters mothers (42) being recycled, after lifting (43) of their pressure, to the hydrolysis (a); (d) separating (20) the gaseous stream (11) enriched in ammonia and carbon dioxide, into a fraction (21 or 56) gaseous enriched in carbon dioxide, evacuated, and an ammoniacal liquid fraction (3) which is recycled to hydrolysis (a), after lifting (7) of its pressure.   2. Method according to claim 1, characterized in that the hydrolysis (1), according to step (a), is carried out at a temperature ranging between 120 and 200 C, preferably 160 C.   3. Method according to claim 1, characterized in that the hydrolysis (1) according to step (a) is carried out at a pressure between 5 and 60 bar, preferably 20 bar.   4. Method according to any one of the preceding claims, characterized in that the stream (11) enriched ammonia gas after condensation, is washed (50) with an amine, for example monoethanolamine, diglycolamine or triethanolamine, to obtain on the one hand, a liquid portion (51) enriched with carbon dioxide, and on the other hand a gaseous portion (52) enriched with ammonia, said liquid portion enriched with carbon dioxide being then separated (55) into carbon dioxide. gaseous carbon (52) and liquid amine (57) recycled to the wash (50).   5. Method according to any one of the preceding claims, characterized in that separates the liquid stream (12) enriched in methionine by staged crystallization (45), to obtain solid methionine, filtered (46) and dried (47). ), and the mother liquors (42).   6. Process according to any one of the preceding claims, characterized in that the hydrolysis (1) according to (a) is carried out in a tubular reactor or in a plurality of stirred reactors (la, lb, 1c, 1d ), arranged in series.